How to Create a Twitter Application:

The first thing you need to do to get your Twitter API key is to create a Twitter application through their site. Visit dev.twitter.com/apps and login to your Twitter account. Then, just fill out the basic information for the application and it’s ready to be published.

Name – This field will be the display name of your application and will be used during user authentication. It will be checked against all other Twitter applications, so make sure to use a unique name.

Description – Write a short description on what you intend to do with the application.

Website – Fill in the full URL (including http://www) of the website you intend to either use the application or make it available for public download.

Callback URL – If you intend to return your users to a specific URL after authentication, specify it here. In basic cases like WordPress widget integration, this field can be left blank.

Read and agree to the Developer Rules of the Road, enter the Captcha phrase, and create! You’re now done creating your application, that wasn't so hard was it?

Application Information

Now that you've created your application, Twitter has assigned you a few data points to work with.

You must create a personal Access Token and Secret key to allow you to unlock personal account functions with your application – just click ‘Create Access Token’ and Twitter will add these data points as well.

If your application requires additional functionality, you can increase the default Access Level from Read-only to Read-Write or even Read-Write-Direct Message. If you’re creating an application that only needs to pull tweets, Read-only is all you need.

In basic cases like WordPress widget integration, all you’ll likely need are the Consumer Key & Secret with the Access Token & Secret. These API keys let Twitter know that you’re a registered Twitter user that has a certain level of access to their API, so keep these keys secret.